Linux utility to determine WWN from a LUN number

Linux utility to determine WWN from a LUN number

[lemons_terry]

Hi

I want to have multipath manage only the CLARiiON LUN that I boot from (LUN 0).  So I know that I can specify the following in /etc/multipath.conf:

blacklist {
	wwid *
	}
blacklist_exceptions {
	wwid nnnnnnnnnn
	}

The wwid value is different for every CLARiiON LUN.  So, if I want to automate the process of adding the 'wwid' value to the blacklist, what utility can I use to specify a LUN number, and find the WWN of the LUN?

Thanks!
tl

Terry Lemons
Backup Platforms Group
EMC² 
where information lives
4400 Computer Drive, MS D239
Westboro MA 01580
Phone: 508 898 7312
Email: Lemons_Terry@emc.com

Re: Linux utility to determine WWN from a LUN number

[Chip Coldwell]

On Thu, 13 Mar 2008, lemons_terry@emc.com wrote:

> Hi
> 
> I want to have multipath manage only the CLARiiON LUN that I boot from (LUN 0).  So I know that I can specify the following in /etc/multipath.conf:
> 
> blacklist {
> 	wwid *
> 	}
> blacklist_exceptions {
> 	wwid nnnnnnnnnn
> 	}
> 
> The wwid value is different for every CLARiiON LUN.  So, if I want to automate the process of adding the 'wwid' value to the blacklist, what utility can I use to specify a LUN number, and find the WWN of the LUN?

I've written one.  Try it!

Easy way:

rpm -ivh http://people.redhat.com/coldwell/coldwell-release-0-1.noarch.rpm
yum install -y scsitool
scsitool --wwid --hbtl --devname

Alternately, you can download source/binaries:

http://people.redhat.com/coldwell/repo/RHEL/5/src/scsitool-0-4.src.rpm
http://people.redhat.com/coldwell/repo/RHEL/5/x86_64/scsitool-0-4.x86_64.rpm

etc.

Chip

-- 
Charles M. "Chip" Coldwell
Senior Software Engineer
Red Hat, Inc
978-392-2426

GPG ID:  852E052F
GPG FPR: 77E5 2B51 4907 F08A 7E92  DE80 AFA9 9A8F 852E 052F

Re: Linux utility to determine WWN from a LUN number

[malahal]

lemons_terry@emc.com [lemons_terry@emc.com] wrote:
> Hi
> 
> I want to have multipath manage only the CLARiiON LUN that I boot from (LUN 0).  So I know that I can specify the following in /etc/multipath.conf:
> 
> blacklist {
> 	wwid *
> 	}
> blacklist_exceptions {
> 	wwid nnnnnnnnnn
> 	}
> 
> The wwid value is different for every CLARiiON LUN.  So, if I want to automate the process of adding the 'wwid' value to the blacklist, what utility can I use to specify a LUN number, and find the WWN of the LUN?
> 
> Thanks!
> tl

lsscsi, lists all your SCSI devices. It should have LUN number and
device name. You can use scsi_id to get WWN. lsscsi uses "sysfs" file
system (/sys/class/scsi_device/ etc), so you should be able to write
your own to suite your exact needs.

RE: Linux utility to determine WWN from a LUN number

[lemons_terry]

>lemons_terry@emc.com [lemons_terry@emc.com] wrote:
>> Hi
>> 
>> I want to have multipath manage only the CLARiiON LUN that I boot
from (LUN 0).  So I know that I can specify the following in
/etc/multipath.conf:
>> 
>> blacklist {
>> 	wwid *
>> 	}
>> blacklist_exceptions {
>> 	wwid nnnnnnnnnn
>> 	}
>> 
>> The wwid value is different for every CLARiiON LUN.  So, if I want to
automate the process of adding the 'wwid' value to the blacklist, what
utility can I use to specify a LUN number, and find the WWN of the LUN?
>> 
>> Thanks!
>> tl
>
>lsscsi, lists all your SCSI devices. It should have LUN number and
>device name. You can use scsi_id to get WWN. lsscsi uses "sysfs" file
>system (/sys/class/scsi_device/ etc), so you should be able to write
>your own to suite your exact needs.

Sorry, but doesn't scsi_id only return what it finds in SCSI VPD pages
80 or 83?  Not all devices provide a WWN in VPD page 83.

tl

Re: Linux utility to determine WWN from a LUN number

[Hannes Reinecke]

lemons_terry@emc.com wrote:
>> lemons_terry@emc.com [lemons_terry@emc.com] wrote:
>>> Hi
>>>
>>> I want to have multipath manage only the CLARiiON LUN that I boot
> from (LUN 0).  So I know that I can specify the following in
> /etc/multipath.conf:
>>> blacklist {
>>> 	wwid *
>>> 	}
>>> blacklist_exceptions {
>>> 	wwid nnnnnnnnnn
>>> 	}
>>>
>>> The wwid value is different for every CLARiiON LUN.  So, if I want to
> automate the process of adding the 'wwid' value to the blacklist, what
> utility can I use to specify a LUN number, and find the WWN of the LUN?
>>> Thanks!
>>> tl
>> lsscsi, lists all your SCSI devices. It should have LUN number and
>> device name. You can use scsi_id to get WWN. lsscsi uses "sysfs" file
>> system (/sys/class/scsi_device/ etc), so you should be able to write
>> your own to suite your exact needs.
> 
> Sorry, but doesn't scsi_id only return what it finds in SCSI VPD pages
> 80 or 83?  Not all devices provide a WWN in VPD page 83.
> 
The WWN is either in VPD page 0x83 or 0x80 (in that order of preference).
You should be using the utility 'scsi_id' to generate the WWN for a given
path (eg call it like 'scsi_id -g -u -s /block/sdX'), as this is the same
program multipath is using.

So the scsi_id program will give a you a mapping sdX -> WWN. And to get
the mapping 'LUN -> sdX' you can simply do a

( cd -P /sys/block/sdX/device; echo ${PWD##*/} )

which will display the SCSI ID of the device; the last number of which is
the LUN presented to the OS.

The remainder is left as an exercise to the reader :-)

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)

RE: Linux utility to determine WWN from a LUN number

[Chip Coldwell]

On Thu, 13 Mar 2008, lemons_terry@emc.com wrote:
> 
> Sorry, but doesn't scsi_id only return what it finds in SCSI VPD pages
> 80 or 83?  Not all devices provide a WWN in VPD page 83.

It's quite a bit more complicated than that.  If a WWN exists on VPD
pages 80 or 83, scsi_id will return that; otherwise it will synthesize
a serial number.

Doug Gilbert and I have exchange some correspondence on the subject of
unifying his lsscsi (and possibly sg3_utils), my scsitool and the udev
scsi_id utility.  At the moment, all of these are drawn from different
code bases.  Doug chose to design lsscsi to use only sysfs information
because he wanted it to be runnable as a non-privileged process.
That's both good and bad: sysfs is shifting sand to build a foundation
on, and so far there is no standard place in sysfs to retrieve a WWN.
Both scsi_id and sg3_utils use SG_IO to do a VPD 0x80/0x83 INQUIRY.

Chip

-- 
Charles M. "Chip" Coldwell
Senior Software Engineer
Red Hat, Inc
978-392-2426

GPG ID:  852E052F
GPG FPR: 77E5 2B51 4907 F08A 7E92  DE80 AFA9 9A8F 852E 052F

Re: Linux utility to determine WWN from a LUN number

[Hannes Reinecke]

Hi Chip,

Chip Coldwell wrote:
> On Thu, 13 Mar 2008, lemons_terry@emc.com wrote:
>> Sorry, but doesn't scsi_id only return what it finds in SCSI VPD pages
>> 80 or 83?  Not all devices provide a WWN in VPD page 83.
> 
> It's quite a bit more complicated than that.  If a WWN exists on VPD
> pages 80 or 83, scsi_id will return that; otherwise it will synthesize
> a serial number.
> 
> Doug Gilbert and I have exchange some correspondence on the subject of
> unifying his lsscsi (and possibly sg3_utils), my scsitool and the udev
> scsi_id utility.  At the moment, all of these are drawn from different
> code bases.  Doug chose to design lsscsi to use only sysfs information
> because he wanted it to be runnable as a non-privileged process.
> That's both good and bad: sysfs is shifting sand to build a foundation
> on, and so far there is no standard place in sysfs to retrieve a WWN.
> Both scsi_id and sg3_utils use SG_IO to do a VPD 0x80/0x83 INQUIRY.
> 
I'd be more than happy to move the scsi_id program out of the udev
codebase and merge it with sg3_utils. Or, possibly better, would
be to have scsi_id use the libraries provided by sg3_utils.
scsi_id is just part of udev as it accidentally ended up there ...

IIRC we even hijacked that out of multipath-tools at one point.
And what's more, it's effectively orphaned as Patrick Mansfield
doesn't seem to work on SCSI things anymore. So moving scsi_id
to a better maintained base would indeed be a good idea.

BTW: what is the main reason for scsitool? Does it have features
which scsi_id and sg3_utils are missing?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)

Re: Linux utility to determine WWN from a LUN number

[Chip Coldwell]

On Fri, 14 Mar 2008, Hannes Reinecke wrote:

> The WWN is either in VPD page 0x83 or 0x80 (in that order of preference).
> You should be using the utility 'scsi_id' to generate the WWN for a given
> path (eg call it like 'scsi_id -g -u -s /block/sdX'), as this is the same
> program multipath is using.

scsi_id comes with udev, and uses an SG_IO to retrieve VPD page 0x83
or 0x80.  It does a little bit more than that, however, and will
return a slightly different WWN than sg3_utils.  According to SPC3, an
Identification Descriptor on VPD page 0x83 begins with a 4-bit code
set, then a 4-bit protocol identifier, then a 4-bit identifier type.
The identifier types are

0x00 vendor specific
0x01 T10 vendor ID based
0x02 EUI-64 based
0x03 NAA (Name Assigning Authority?)
0x04 relative target port id
0x05 target port group
0x06 logical unit group
0x07 MD5 logical unit id
0x08 SCSI name string

When the scsi_id program parses the VPD 0x83 data, it will prepend
this number to the identifier found in the VPD 0x83 descriptor.
sg3_utils does not do this.  For example:

# scsi_id -g -s /block/sda
3600601601040190000c7da47f286dc11

# sg_inq -p 0x83 /dev/sda
VPD INQUIRY: Device Identification page
  Designation descriptor number 1, descriptor length: 20
    id_type: NAA,  code_set: Binary
    associated with the addressed logical unit
      NAA 6, IEEE Company_id: 0x6016
      Vendor Specific Identifier: 0x10401900
      Vendor Specific Identifier Extension: 0xc7da47f286dc11
      [0x600601601040190000c7da47f286dc11]
  Designation descriptor number 2, descriptor length: 20
    id_type: vendor specific [0x0],  code_set: Binary
    associated with the addressed logical unit
 00     00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00    ................
  Designation descriptor number 3, descriptor length: 8
    id_type: Relative target port,  code_set: Binary
    associated with the target port
      Relative target port: 0x1
  Designation descriptor number 4, descriptor length: 8
    id_type: Target port group,  code_set: Binary
    associated with the target port
      Target port group: 0x1

In my scsitool, I chose to emulate the scsi_id behavior

# scsitool --devname=sda --hbtl --wwid
sda 0:0:0:0 3600601601040190000c7da47f286dc11 

> So the scsi_id program will give a you a mapping sdX -> WWN. And to get
> the mapping 'LUN -> sdX' you can simply do a
> 
> ( cd -P /sys/block/sdX/device; echo ${PWD##*/} )
> 
> which will display the SCSI ID of the device; the last number of which is
> the LUN presented to the OS.
>
> The remainder is left as an exercise to the reader :-)

The --hbtl switch to scsitool gives host:bus:target:lun.  If the
device is multipathed, you will see the same lun with different h:b:t
combinations.  So what you could do is

scsitool --wwid --hbtl | awk '/:2 $/ { print $1 }' | sort -u

That gives you the WWID of LUN 2.  Unfortunately, there seems to be a
trailing space in the output ... I'll fix that and turn a rev.

Chip

-- 
Charles M. "Chip" Coldwell
Senior Software Engineer
Red Hat, Inc
978-392-2426

GPG ID:  852E052F
GPG FPR: 77E5 2B51 4907 F08A 7E92  DE80 AFA9 9A8F 852E 052F

Re: Linux utility to determine WWN from a LUN number

[Chip Coldwell]

On Fri, 14 Mar 2008, Hannes Reinecke wrote:
> 
> BTW: what is the main reason for scsitool?

The main idea with scsitool is to be able to select, sort and output
properties of SCSI disks.  The properties it supports are

--devname (sda, sdb, etc.)
--hbtl (host:bus:target:lun nexus)
--wwid
--target-wwnn
--target-wwpn
--host-wwnn
--host-wwpn
--vendor
--model
--driver (e.g. lpfc, qla2xxx)

any of these options can be supplied bare (in which case it matches
all devices) or with a match value.  For example:

# scsitool --driver=qla2xxx --hbtl --devname
qla2xxx 1:0:0:1 sdo 
qla2xxx 1:0:1:1 sdp 
qla2xxx 1:0:2:0 sdq 
qla2xxx 1:0:2:1 sdr 
qla2xxx 1:0:2:2 sds 
qla2xxx 1:0:3:0 sdt 
qla2xxx 1:0:3:1 sdu 
qla2xxx 1:0:3:2 sdv 
qla2xxx 1:0:4:0 sdw 
qla2xxx 1:0:4:1 sdx 
qla2xxx 1:0:4:2 sdy 
qla2xxx 1:0:5:0 sdz 
qla2xxx 1:0:5:1 sdaa 
qla2xxx 1:0:5:2 sdab 

For any combination, the output only includes the properties
specified, and is sorted by those properties in the order that those
properties are specified.  So, for example, to find all the WWIDs on
the system

]# scsitool --wwid --devname
35000c5000020d907 sdac 
35000c5000020d933 sdad 
3600508b400105e210000900000550000 sdm 
3600508b400105e210000900000550000 sdn 
3600508b400105e210000900000550000 sdo 
3600508b400105e210000900000550000 sdp 
3600601601040190000c7da47f286dc11 sda 
3600601601040190000c7da47f286dc11 sdd 
3600601601040190000c7da47f286dc11 sdg 
3600601601040190000c7da47f286dc11 sdj 
3600601601040190000c7da47f286dc11 sdq 
3600601601040190000c7da47f286dc11 sdt 
3600601601040190000c7da47f286dc11 sdw 
3600601601040190000c7da47f286dc11 sdz 
360060160104019008e275c5af286dc11 sdc 
360060160104019008e275c5af286dc11 sdf 
360060160104019008e275c5af286dc11 sdi 
360060160104019008e275c5af286dc11 sdl 
360060160104019008e275c5af286dc11 sds 
360060160104019008e275c5af286dc11 sdv 
360060160104019008e275c5af286dc11 sdy 
360060160104019008e275c5af286dc11 sdab 
36006016010401900be062253f286dc11 sdb 
36006016010401900be062253f286dc11 sde 
36006016010401900be062253f286dc11 sdh 
36006016010401900be062253f286dc11 sdk 
36006016010401900be062253f286dc11 sdr 
36006016010401900be062253f286dc11 sdu 
36006016010401900be062253f286dc11 sdx 
36006016010401900be062253f286dc11 sdaa 

Now select the device names that correspond to just one WWID

# scsitool --wwid=3600601601040190000c7da47f286dc11 --devname
3600601601040190000c7da47f286dc11 sda 
3600601601040190000c7da47f286dc11 sdd 
3600601601040190000c7da47f286dc11 sdg 
3600601601040190000c7da47f286dc11 sdj 
3600601601040190000c7da47f286dc11 sdq 
3600601601040190000c7da47f286dc11 sdt 
3600601601040190000c7da47f286dc11 sdw 
3600601601040190000c7da47f286dc11 sdz 

The hope is that scsitool will be helpful for people writing scripts.
As a trivial example, if I wanted only the device names above:

# scsitool --wwid=3600601601040190000c7da47f286dc11 --devname | cut -d' ' -f2
sda
sdd
sdg
sdj
sdq
sdt
sdw
sdz

> Does it have features which scsi_id and sg3_utils are missing?

I think the answer, in a mathematical sense, is "no".  However, I
found it so cumbersome to combine the existing tools in scripts that
it was worthwhile for me to write a new one from scratch.  In
addition, in deployments with thousands of LUNs, I think combining the
existing tools in scripts can turn out to be rather slow.

Chip

-- 
Charles M. "Chip" Coldwell
Senior Software Engineer
Red Hat, Inc
978-392-2426

GPG ID:  852E052F
GPG FPR: 77E5 2B51 4907 F08A 7E92  DE80 AFA9 9A8F 852E 052F

Re: Linux utility to determine WWN from a LUN number

[Hannes Reinecke]

Chip Coldwell wrote:
> On Fri, 14 Mar 2008, Hannes Reinecke wrote:
>> BTW: what is the main reason for scsitool?
> 
> The main idea with scsitool is to be able to select, sort and output
> properties of SCSI disks.  The properties it supports are
> 
> --devname (sda, sdb, etc.)
> --hbtl (host:bus:target:lun nexus)
> --wwid
> --target-wwnn
> --target-wwpn
> --host-wwnn
> --host-wwpn
> --vendor
> --model
> --driver (e.g. lpfc, qla2xxx)
> 
[ .. ]
> 
Ah, I see. So basically combining lsscsi and scsi_id.

>> Does it have features which scsi_id and sg3_utils are missing?
> 
> I think the answer, in a mathematical sense, is "no".  However, I
> found it so cumbersome to combine the existing tools in scripts that
> it was worthwhile for me to write a new one from scratch.  In
> addition, in deployments with thousands of LUNs, I think combining the
> existing tools in scripts can turn out to be rather slow.
> 
So the logical choice would be to include scsitool in sg3_utils,
I believe. And scsi_id, too, for good measure. Just so that we're
on one page with generating unique identifiers for udev :-)

As already mentioned, I'm not especially partial as to _where_
scsi_id is kept. I'd happily move it over to sg3_utils.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)

Re: Linux utility to determine WWN from a LUN number

[Chip Coldwell]

On Fri, 14 Mar 2008, Hannes Reinecke wrote:

> Ah, I see. So basically combining lsscsi and scsi_id.

Yes, although the output format is more configurable than lsscsi.

> As already mentioned, I'm not especially partial as to _where_
> scsi_id is kept. I'd happily move it over to sg3_utils.

Ideally, we would also factor out all the common code among the three
into a common library.

Chip

-- 
Charles M. "Chip" Coldwell
Senior Software Engineer
Red Hat, Inc
978-392-2426

GPG ID:  852E052F
GPG FPR: 77E5 2B51 4907 F08A 7E92  DE80 AFA9 9A8F 852E 052F

Re: Linux utility to determine WWN from a LUN number

[Hannes Reinecke]

Chip Coldwell wrote:
> On Fri, 14 Mar 2008, Hannes Reinecke wrote:
> 
>> Ah, I see. So basically combining lsscsi and scsi_id.
> 
> Yes, although the output format is more configurable than lsscsi.
> 
>> As already mentioned, I'm not especially partial as to _where_
>> scsi_id is kept. I'd happily move it over to sg3_utils.
> 
> Ideally, we would also factor out all the common code among the three
> into a common library.
> 
sg3-utils already has such a library. Would be fairly easy to use that ...

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)

RE: Linux utility to determine WWN from a LUN number

[lemons_terry]

 

-----Original Message-----
From: dm-devel-bounces@redhat.com [mailto:dm-devel-bounces@redhat.com]
On Behalf Of Hannes Reinecke
Sent: Friday, March 14, 2008 3:13 AM
To: device-mapper development
Subject: Re: [dm-devel] Linux utility to determine WWN from a LUN number

Hannes Reinecke wrote:
>The WWN is either in VPD page 0x83 or 0x80 (in that order of
preference).

In my experience, not always.  I've seen FC products (especially
autochanger and tape devices) that do not embed a WWN in VPD page 0x83.
Some embed a non-unique WWN value.

tl